String Theory Bluestar

'String Theory' is a compact selection of threadleaf bluestar (Amsonia hubrichtii), developed at Walters Gardens in Michigan and sold under the Proven Winners label. It keeps the fine, needle-like foliage and golden-orange autumn color of the species in a clump about half the size, roughly 18 to 22 inches tall and up to 3 feet wide. Pale periwinkle blue star flowers open in late spring, a little later than most other bluestars, and the foliage stays a healthy dark green through summer instead of fading yellow early.

Like its parent, it is a plant of the Ouachita region that has proved hardy well beyond it. It grows in full sun to part shade, takes average garden soil, and tolerates heat and humidity. Established clumps shrug off dry spells, and the milky sap keeps deer and rabbits away. Growth is slow at first and picks up with age, so give it a few seasons before judging it. A light shearing right after bloom keeps the mound tidy, though the compact habit needs far less of that than the species.

The cultivar is patented (PP34419), so propagate by division only for your own garden and buy new plants rather than propagating to sell. Pair it with the taller species form, see Hubricht's Bluestar, where a bigger fall show is wanted.